• temperature

• heat

• conduction

• radiation

Particles in Motion

• convection

• vaporization

• thermal conductor

• thermal insulator

Lesson 3-1 Particles in Motion A. Kinetic Molecular Theory 1. The transfer of thermal energy

depends on the movement of particles in the material.

Kinetic Molecular Theory

Lesson 3-1 2. The kinetic molecular theory of matter explains how particles move.

a. Particles make up all matter. b. Particles are in constant, random motion. c. Particles constantly collide with each

other and with thewalls of their container.

Lesson 3-1Kinetic Molecular Theory (cont.)

What are the three points of the kinetic molecular theory?

Lesson 3-1 3. Temperature is the measure of the

average kinetic energy of the particles in a material.

a. If the particles in a material have little kinetic energy, the material feels cold.

b. The SI unit for temperature is Kelvin (K).

c. Another temperature unit often used by scientists is Celsius (C).

Kinetic Molecular Theory (cont.)

Lesson 3-1When water is cooled to near its freezing point, interactions between water molecules push the molecules apart.

Kinetic Molecular Theory (cont.)

Lesson 3-1 4. Thermal expansion is the increase

in volume that a material undergoeswhen its temperature increases.

a. At higher temperatures, the particles in matter move faster, requiring more volume because they collide more often,pushing each other apart.

b. Thermal contraction is the decrease in a material’s volume when its temperature decreases.

Kinetic Molecular Theory (cont.)

Lesson 3-1When you put a warm bottle of water in a cold refrigerator, thermal energy is transferred.

Lesson 3-1 5. Kinetic energy is transferred from

one material to another one when their particles collide.

6. Heat is the movement of thermal energy from a region of higher temperature to a region of lower temperature.

7. Materials are said to be in thermal equilibrium when the temperatures ofmaterials that are touching are equal.

Kinetic Molecular Theory (cont.)

Lesson 3-1Kinetic Molecular Theory (cont.)

equilibriumfrom Latin aequus, means “equal”; and libra, means “a balance or scale”

Lesson 3-2 B. Heat Transfer 1. Conduction is the transfer of

thermal energy due to collisionsbetween particles in matter.

2. Radiation is the transfer of thermal energy by electromagneticwaves.

3. Convection is the transfer of thermal energy by the movementof the particles from one part of a material to another.

Lesson 3-2Conduction, radiation, and convection are ways in which thermal energy is transferred.

Lesson 3-2Heat Transfer (cont.)

In what three ways is thermal energy transferred?

Lesson 3-3

C. Heat and Changes of State 1. When thermal energy is added to

solid ice, its temperature increases until it starts to melt, changing to liquid water.

2. When thermal energy is removed from liquid water, its temperaturedecreases until it starts to freeze, changing to solid ice.

Heat and Changes of State

Lesson 3-3

3. When thermal energy is added to liquid water, its temperature increases until it starts to vaporize, changing to a gas.

4. When thermal energy is removed from a gas, it changes to a(n) liquid through a process called condensation.

Heat and Changes of State (cont.)

Lesson 3-3

5. Sublimation occurs when a solid absorbs energy and changes directly to a gas without first becoming a(n) liquid.

6. Deposition occurs when a gas changes directly to a solid withoutfirst becoming a(n) liquid.

Heat and Changes of State (cont.)

Lesson 3-3Heat and Changes of State (cont.)

sublimeScience Use to change from a solid state to a gas state without passing through the liquid stateCommon Use inspiring awe; supreme, outstanding, or lofty in thought or language

Lesson 3-4

D. Conductors and Insulators 1. Thermal energy moves quickly in a

thermal conductor. 2. Thermal energy moves slowly in a

thermal insulator

Conductors and Insulators

Lesson 3-4Conductors and Insulators (cont.)

How do thermal conductors differ from thermal insulator?

Lesson 3 - VS• The kinetic molecular theory

explains how particles move in matter.

Lesson 3 - VS• Thermal energy is transferred in

various ways by particles and waves.

• Materials vary in how well they conduct thermal energy.